Nissan and Subaru Head Bolt Thread Repair Kit – Solved

WiseAutoTools.com © Summary: Head bolt thread repair kits for repairing head-bolt threads in the cylinder block if done properly can save thousands of dollars compared to replacing engine blocks. Advantages of using Time Sert solid bushing type inserts over a thin coils of wire like Heli Coil uses. Helicoil is the better known brand however, clearly is not the better thread repair system. Both brands have kits for M11x1.25 head bolts which are commonly found in Nissan and Infiniti engines (and Subaru). Read on to learn why Time Sert is better. Also, learn about a thread repair kit that can even save a block that has had a Heli Coil fail making the hole too large for a standard repair. These questions and more answered below by a master auto tech that fields thread repair questions like this everyday. Also see the video discussing differences in Helicoil VS Time Sert. Click the following current pricing on the Time Sert 11125 (commonly used on Nissan and Subaru). For over-size repairs that use the original size head bolts see Time Sert 11125BS. There's also a very specific kit for Subaru race applications which is the Time Sert 15100. See below for more information.

First of all, many may be wondering why manufacturers use aluminum in their engines since steel or cast iron is much stronger. The answer is simple. Weight. By using aluminum the over-all vehicle weight is decreased significantly which helps the manufacturer obtain higher miles per gallon of gas that we all want. The problem is, which you may already know since you’re reading this page is that the aluminum threads can fail. Head bolt threads need to be repaired reliably or else a head gasket leak is inevitable. And there’s a lot of work involved in tearing down an engine to that extent. So it only makes since to use the best thread repair kit available, since no one wants to go through the trouble and expense of re-doing a head gasket job because of a failed inferior repair.

Question – Why do head bolt threads in the cylinder block to fail to begin with?

Answer – Head bolt threads in engine blocks have to survive many cycles of heating and cooling. Over time, even with proper torque the aluminum threads can deteriorate which can cause them to fail. Aluminum, is the material that the block consists of, is weaker than steel head bolts so it’s no wonder which are the weakest link. Sometimes a coolant leak can lead to overheating and can in turn cause the head gasket to fail. The over heat condition can then cause the head bolt threads to fail. Other times the threads could fail first resulting in head gasket failure. Either way, using Time Sert carbon steel inserts will help insure a lasting repair. After all steel is stronger than aluminum.

Question – I’ve heard of Helicoils but have never heard of Time Serts. Why do you say Time Sert is better?

Answer – Hands down, Helicoil is the best known brand of thread repair. Many people don’t know that Time Sert has many advantages over Helicoil, especially when it comes to aluminum thread repair. Below is what Time Sert says about the advantages of Time Sert solid inserts over thin coils like Helicoil.

TIME-SERT® is a thin wall, solid bushing, self locking insert with positive placement.

TIME-SERT® inserts are a thin wall solid bushing insert. This guarantees easy installation and allows for full load use of tapped hole, ensuring protection against stress and vibration.
TIME-SERT® inserts are “timed” internal to external which gives a very thin wall thickness which means TIME-SERT inserts can be installed in areas of limited space and clearance.
TIME-SERT® being a solid bushing insert gives it added strength, easily withstands high temperatures without damage or deforming. TIME-SERT® inserts have no prongs or tangs to break off or deal with down in the hole, which can be a problem in deep holes.

TIME-SERT® inserts are self-locking having an actual locking feature which will prevent them from coming out when a bolt is removed. On installation the bottom few internal threads of the insert are cold rolled to expand into the mating external threads of the base material locking the insert in place.

TIME-SERT® inserts have a flange, which will give them a positive placement on installation for “accurate specific depths”. This ensures that the insert does not wind down into the threaded hole.

Thin wall, self locking , solid bushing insert with positive placement.

Customers have asked if they may also use Loctite® adhesives for additional strength. Yes you may due to the solid wall design. There is no danger of loctite passing thru the threads of the insert and locking up the bolt as in coil types. Time-Sert inserts are used in Aluminum, cast iron, steels and even some hard plastics. MADE IN THE USA.

Question – I have a Heli Coil repair that failed. When torqueing the head bolts it just pulled out. I tried putting in a another coil insert but it’s not grabbing. Do you have a kit that will work?

Answer – Yes. The Time Sert “BIG-SERT” is an over size repair that works when Helicoil has failed to hold. The M11x1.25 BIG SERT kit is the 11125BS.

Question – I already have drill bits. I just need to buy the tap and the insert. Will just sell me just the tap and an insert?

Answer – Besides. inserts, we don’t sell just pieces of a kit, unless our customer needs a replacement tool for a kit previously purchased. The reason is because we don’t want to set you up for failure. There really is a reason for every tool in a Time Sert kit. For example, the core drill bit is not a “regular” drill bit. It has a stepped design and has a counter-sink built in so that the insert can be installed flush. The line-up bushing along with the drill fixture plate helps insure that drilling is done straight. The installation driver finishes cold rolling the insert and expanding it at the bottom holding it in place. The permanent, high temp red loctite also aids in making this a permanent repair.

Question – After a Helicoil fails can I use the 11125 kit?

Answer – No. The Time Sert 11125 kit is a “first time” repair. Meaning no other repair like Helicoil or competitive brand has been used. The Big Sert kit can be used, pn 11125BS. It’s inserts are a larger outside diameter and still accepts the same size M11x1.25 head bolt.

Question – I have a 11125 kit and just need one Big Sert. Can I install Big Serts with my regular size 11125 kit?

Answer – No. Since the Big Sert has a larger outside diameter, the tooling is different. For this reason the Big Sert 11125BS kit will be needed.

For even more information, see our main page with many more articles and videos on how to repair stripped threads.

We've been selling specialty tools and aluminum thread repair kits since 2005. Call for assistance in finding the best spark plug thread repair kit for your situation at 800-734-8665 or provide your details by using our Contact Form.